The present invention relates generally to the field of airbag cushions that can be deployed in two different volumes or shapes.
Airbags can inflate into different volumes. Conventionally, airbags with dual-volumes incorporate tethers. The tethers initially restrict the airbag cushion to a particular volume that is relatively smaller than the full volume that the airbag cushion is capable of achieving. The tether anchors are released by an electro-mechanical or electronically triggered pyro-mechanical control device in order to inflate the airbag cushion to the full volume.
Conventionally, a movable vent mechanism is incorporated into the airbags with tethers. Sliding pins or clamps are often included in the tether release mechanism to hold the tether in position in “small bag” mode and to release the airbag when transitioning into “large bag” mode. This release mechanism is commonly associated with a mechanical gas vent in the open position to release a portion of the generated gas into the surrounding space rather than into the airbag to allow for a reduced pressure in the “small bag” condition. This vent is closed to make a higher pressure when the tether anchors are released in the “large bag” mode. In the default condition, the airbag is in the “small bag” mode. The default condition is “small bag” mode because it is easier to release a pin or clamp on the tether than to catch a released tether after the airbag cushion begins to inflate.